Compounds derived from 3-cyanoquinoline have been shown to have anti-tumor activity, which may make them useful as chemotherapeutic agents in treating various cancers, including but not limited to, pancreatic cancer, melanoma, lymphatic cancer, parotid tumors, Barrett's esophagus, esophageal carcinomas, head and neck tumors, ovarian cancer, breast cancer, epidermoid tumors, cancers of major organs, such as kidney, bladder, larynx, stomach, and lung, colonic polyps and colorectal cancer and prostate cancer. Examples of compounds derived from 3-cyanoquinoline are disclosed and shown to possess anti-tumor activity in U.S. Pat. Nos. 6,002,008; 6,432,979; and 6,288,082. One limitation of certain 3-cyanoquinoline compounds is that they are not water soluble in a free base form.
The crystalline form of a particular drug as a salt, a hydrate and/or any polymorph thereof is often one important determinant of the drug's ease of preparation, stability, water solubility, storage stability, ease of formulation and in-vivo pharmacology. It is possible that one crystalline form is preferable over another where certain aspects such as ease of preparation, stability, water solubility and/or superior pharmacokinetics are deemed to be critical. Crystalline forms of (E)-N-{4-[3-chloro-4-(2-pyridinylmethoxy)anilino]-3-cyano-7-ethoxy-6-quinolinyl}-4-(dimethylamino)-2-butenamide salts that possess a higher degree of water solubility than the free base but are stable fulfill an unmet need for stable, crystalline, water-soluble forms of substituted 3-cyanoquinoline compounds that selectively inhibit kinase activity, which in turn inhibit cell proliferation and tumorigenesis.